Which specific behavior contributes to the bird being difficult to observe even where locally common?

It maneuvers by darting rapidly between bushes just one or two meters above the forest floor.

A major factor contributing to the perception of the Oriental Dwarf Kingfisher's rarity is its intensely secretive lifestyle. It is characterized as very shy and skittish, preferring to remain concealed within dense cover rather than perching openly. Its movement involves rapidly darting between bushes and trees, frequently making low-level passes just one or two meters above the forest floor or undergrowth. This combination of small size and low, quick movement allows it to slip out of view instantly, making observation challenging even for experienced bird watchers who typically scan higher vantage points.